# Notification class The Notification plugin. This plugin sends a few types of notifications: `success`, `info` and `warning`. The notifications need to be handled and displayed by a plugin responsible for showing the UI of the notifications. Using this plugin for dispatching notifications makes it possible to switch the notifications UI. Note that every unhandled and not stopped `warning` notification will be displayed as a system alert. See [`showWarning`](#function-showWarning). [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L22) ## Properties ### `context: ContextInterface` _(readonly)_ The context or editor instance. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/contextplugin.ts#L45) #### Static properties ### `isContextPlugin: true` _(readonly)_ [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/contextplugin.ts#L66) ### `isOfficialPlugin: true` _(readonly)_ [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L33) ### `isPremiumPlugin: boolean` _(readonly)_ [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/contextplugin.ts#L80) ### `pluginName: 'Notification'` _(readonly)_ [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L26) ## Methods ### `constructor( context )` _(inherited)_ Creates a new plugin instance. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/contextplugin.ts#L50) #### Parameters * `context: Editor | Context` ### `bind( bindProperties ) → ObservableMultiBindChain` _(inherited)_ Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface. Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples. Consider two objects: a `button` and an associated `command` (both `Observable`). A simple property binding could be as follows: ```typescript button.bind( 'isEnabled' ).to( command, 'isEnabled' ); ``` or even shorter: ```typescript button.bind( 'isEnabled' ).to( command ); ``` which works in the following way: * `button.isEnabled` **instantly equals** `command.isEnabled`, * whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value. **Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind). You can also "rename" the property in the binding by specifying the new name in the `to()` chain: ```typescript button.bind( 'isEnabled' ).to( command, 'isWorking' ); ``` It is possible to bind more than one property at a time to shorten the code: ```typescript button.bind( 'isEnabled', 'value' ).to( command ); ``` which corresponds to: ```typescript button.bind( 'isEnabled' ).to( command ); button.bind( 'value' ).to( command ); ``` The binding can include more than one observable, combining multiple data sources in a custom callback: ```typescript button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible', ( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible ); ``` Using a custom callback allows processing the value before passing it to the target property: ```typescript button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' ); ``` It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code: ```typescript button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled', ( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled ); ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1074) #### Parameters * `bindProperties: Array<'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'destroy' | 'context' | 'init' | 'showSuccess' | 'showInfo' | 'showWarning'>` Observable properties that will be bound to other observable(s). #### Returns * `ObservableMultiBindChain` The bind chain with the `to()` and `toMany()` methods. ### `bind( bindProperty1, bindProperty2 ) → ObservableDualBindChain` _(inherited)_ Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface. Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples. Consider two objects: a `button` and an associated `command` (both `Observable`). A simple property binding could be as follows: ```typescript button.bind( 'isEnabled' ).to( command, 'isEnabled' ); ``` or even shorter: ```typescript button.bind( 'isEnabled' ).to( command ); ``` which works in the following way: * `button.isEnabled` **instantly equals** `command.isEnabled`, * whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value. **Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind). You can also "rename" the property in the binding by specifying the new name in the `to()` chain: ```typescript button.bind( 'isEnabled' ).to( command, 'isWorking' ); ``` It is possible to bind more than one property at a time to shorten the code: ```typescript button.bind( 'isEnabled', 'value' ).to( command ); ``` which corresponds to: ```typescript button.bind( 'isEnabled' ).to( command ); button.bind( 'value' ).to( command ); ``` The binding can include more than one observable, combining multiple data sources in a custom callback: ```typescript button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible', ( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible ); ``` Using a custom callback allows processing the value before passing it to the target property: ```typescript button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' ); ``` It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code: ```typescript button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled', ( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled ); ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L996) #### Type parameters * * `K1` * `K2` #### Parameters * `bindProperty1: K1` Observable property that will be bound to other observable(s). * `bindProperty2: K2` Observable property that will be bound to other observable(s). #### Returns * `ObservableDualBindChain` The bind chain with the `to()` and `toMany()` methods. ### `bind( bindProperty ) → ObservableSingleBindChain` _(inherited)_ Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface. Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples. Consider two objects: a `button` and an associated `command` (both `Observable`). A simple property binding could be as follows: ```typescript button.bind( 'isEnabled' ).to( command, 'isEnabled' ); ``` or even shorter: ```typescript button.bind( 'isEnabled' ).to( command ); ``` which works in the following way: * `button.isEnabled` **instantly equals** `command.isEnabled`, * whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value. **Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind). You can also "rename" the property in the binding by specifying the new name in the `to()` chain: ```typescript button.bind( 'isEnabled' ).to( command, 'isWorking' ); ``` It is possible to bind more than one property at a time to shorten the code: ```typescript button.bind( 'isEnabled', 'value' ).to( command ); ``` which corresponds to: ```typescript button.bind( 'isEnabled' ).to( command ); button.bind( 'value' ).to( command ); ``` The binding can include more than one observable, combining multiple data sources in a custom callback: ```typescript button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible', ( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible ); ``` Using a custom callback allows processing the value before passing it to the target property: ```typescript button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' ); ``` It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code: ```typescript button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled', ( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled ); ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L918) #### Type parameters * `K` #### Parameters * `bindProperty: K` Observable property that will be bound to other observable(s). #### Returns * `ObservableSingleBindChain` The bind chain with the `to()` and `toMany()` methods. ### `decorate( methodName ) → void` _(inherited)_ Turns the given methods of this object into event-based ones. This means that the new method will fire an event (named after the method) and the original action will be plugged as a listener to that event. Read more in the [dedicated](../framework/deep-dive/observables.md#decorating-object-methods) guide covering the topic of decorating methods with some additional examples. Decorating the method does not change its behavior (it only adds an event), but it allows to modify it later on by listening to the method's event. For example, to cancel the method execution the event can be [stopped](module_utils_eventinfo-EventInfo.md#member-stop): ```typescript class Foo extends ObservableMixin() { constructor() { super(); this.decorate( 'method' ); } method() { console.log( 'called!' ); } } const foo = new Foo(); foo.on( 'method', ( evt ) => { evt.stop(); }, { priority: 'high' } ); foo.method(); // Nothing is logged. ``` **Note**: The high [priority](module_utils_priorities-PriorityString.md) listener has been used to execute this particular callback before the one which calls the original method (which uses the "normal" priority). It is also possible to change the returned value: ```typescript foo.on( 'method', ( evt ) => { evt.return = 'Foo!'; } ); foo.method(); // -> 'Foo' ``` Finally, it is possible to access and modify the arguments the method is called with: ```typescript method( a, b ) { console.log( `${ a }, ${ b }` ); } // ... foo.on( 'method', ( evt, args ) => { args[ 0 ] = 3; console.log( args[ 1 ] ); // -> 2 }, { priority: 'high' } ); foo.method( 1, 2 ); // -> '3, 2' ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1159) #### Parameters * `methodName: 'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'destroy' | 'context' | 'init' | 'showSuccess' | 'showInfo' | 'showWarning'` Name of the method to decorate. #### Returns * `void` ### `delegate( events ) → EmitterMixinDelegateChain` _(inherited)_ Delegates selected events to another [`Emitter`](module_utils_emittermixin-Emitter.md). For instance: ```typescript emitterA.delegate( 'eventX' ).to( emitterB ); emitterA.delegate( 'eventX', 'eventY' ).to( emitterC ); ``` then `eventX` is delegated (fired by) `emitterB` and `emitterC` along with `data`: ```typescript emitterA.fire( 'eventX', data ); ``` and `eventY` is delegated (fired by) `emitterC` along with `data`: ```typescript emitterA.fire( 'eventY', data ); ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L539) #### Parameters * `events: Array` Event names that will be delegated to another emitter. #### Returns * `EmitterMixinDelegateChain` ### `destroy() → void` _(inherited)_ Destroys the plugin. **Note:** This method is optional. A plugin instance does not need to have it defined. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/contextplugin.ts#L59) #### Returns * `void` ### `fire( eventOrInfo, args ) → GetEventInfo[ 'return' ]` _(inherited)_ Fires an event, executing all callbacks registered for it. The first parameter passed to callbacks is an [`EventInfo`](module_utils_eventinfo-EventInfo.md) object, followed by the optional `args` provided in the `fire()` method call. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L512) #### Type parameters * `TEvent: extends BaseEvent` The type describing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md). #### Parameters * `eventOrInfo: GetNameOrEventInfo` The name of the event or `EventInfo` object if event is delegated. * `args: TEvent[ 'args' ]` Additional arguments to be passed to the callbacks. #### Returns * `GetEventInfo[ 'return' ]` By default the method returns `undefined`. However, the return value can be changed by listeners through modification of the [`evt.return`](module_utils_eventinfo-EventInfo.md#member-return)'s property (the event info is the first param of every callback). ### `init() → void` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L40) #### Returns * `void` ### `listenTo( emitter, event, callback, options? ) → void` _(inherited)_ Registers a callback function to be executed when an event is fired in a specific (emitter) object. Events can be grouped in namespaces using `:`. When namespaced event is fired, it additionally fires all callbacks for that namespace. ```typescript // myEmitter.on( ... ) is a shorthand for myEmitter.listenTo( myEmitter, ... ). myEmitter.on( 'myGroup', genericCallback ); myEmitter.on( 'myGroup:myEvent', specificCallback ); // genericCallback is fired. myEmitter.fire( 'myGroup' ); // both genericCallback and specificCallback are fired. myEmitter.fire( 'myGroup:myEvent' ); // genericCallback is fired even though there are no callbacks for "foo". myEmitter.fire( 'myGroup:foo' ); ``` An event callback can [stop the event](module_utils_eventinfo-EventInfo.md#member-stop) and set the [return value](module_utils_eventinfo-EventInfo.md#member-return) of the [`fire`](#function-fire) method. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L475) #### Type parameters * `TEvent: extends BaseEvent` The type describing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md). #### Parameters * `emitter: Emitter` The object that fires the event. * `event: TEvent[ 'name' ]` The name of the event. * `callback: GetCallback` The function to be called on event. * `options?: GetCallbackOptions` Additional options. #### Returns * `void` ### `off( event, callback ) → void` _(inherited)_ Stops executing the callback on the given event. Shorthand for [`this.stopListening( this, event, callback )`](#function-stopListening:BASE_STOP). [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L444) #### Parameters * `event: string` The name of the event. * `callback: Function` The function to stop being called. #### Returns * `void` ### `on( event, callback, options? ) → void` _(inherited)_ Registers a callback function to be executed when an event is fired. Shorthand for [`this.listenTo( this, event, callback, options )`](#function-listenTo:BASE_EMITTER) (it makes the emitter listen on itself). [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L416) #### Type parameters * `TEvent: extends BaseEvent` The type descibing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md). #### Parameters * `event: TEvent[ 'name' ]` The name of the event. * `callback: GetCallback` The function to be called on event. * `options?: GetCallbackOptions` Additional options. #### Returns * `void` ### `once( event, callback, options? ) → void` _(inherited)_ Registers a callback function to be executed on the next time the event is fired only. This is similar to calling [`on`](#function-on) followed by [`off`](#function-off) in the callback. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L431) #### Type parameters * `TEvent: extends BaseEvent` The type descibing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md). #### Parameters * `event: TEvent[ 'name' ]` The name of the event. * `callback: GetCallback` The function to be called on event. * `options?: GetCallbackOptions` Additional options. #### Returns * `void` ### `set( values ) → void` _(inherited)_ Creates and sets the value of an observable properties of this object. Such a property becomes a part of the state and is observable. It accepts a single object literal containing key/value pairs with properties to be set. This method throws the `observable-set-cannot-override` error if the observable instance already has a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that `foo.set( 'bar', 1 )` may be slightly slower than `foo.bar = 1`. In TypeScript, those properties should be declared in class using `declare` keyword. In example: ```typescript public declare myProp1: number; public declare myProp2: string; constructor() { this.set( { 'myProp1: 2, 'myProp2: 'foo' } ); } ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L843) #### Parameters * `values: object & object` An object with `name=>value` pairs. #### Returns * `void` ### `set( name, value ) → void` _(inherited)_ Creates and sets the value of an observable property of this object. Such a property becomes a part of the state and is observable. This method throws the `observable-set-cannot-override` error if the observable instance already has a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that `foo.set( 'bar', 1 )` may be slightly slower than `foo.bar = 1`. In TypeScript, those properties should be declared in class using `declare` keyword. In example: ```typescript public declare myProp: number; constructor() { this.set( 'myProp', 2 ); } ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L815) #### Type parameters * `K` #### Parameters * `name: K` The property's name. * `value: Notification[ K ]` The property's value. #### Returns * `void` ### `showInfo( message, data = { data.namespace?, data.title? } ) → void` Shows an information notification. By default, it fires the [`show:info` event](#event-show:info) with the given `data`. The event namespace can be extended using the `data.namespace` option. For example: ```typescript showInfo( 'Editor is offline.', { namespace: 'editor:status' } ); ``` will fire the `show:info:editor:status` event. You can provide the title of the notification: ```typescript showInfo( 'Editor is offline.', { title: 'Network information' } ); ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L113) #### Parameters * `message: string` The content of the notification. * `data: object` Additional data. Properties * `data.namespace?: string` Additional event namespace. * `data.title?: string` The title of the notification. Defaults to `{}` #### Returns * `void` ### `showSuccess( message, data = { data.namespace?, data.title? } ) → void` Shows a success notification. By default, it fires the [`show:success` event](#event-show:success) with the given `data`. The event namespace can be extended using the `data.namespace` option. For example: ```typescript showSuccess( 'Image is uploaded.', { namespace: 'upload:image' } ); ``` will fire the `show:success:upload:image` event. You can provide the title of the notification: ```typescript showSuccess( 'Image is uploaded.', { title: 'Image upload success' } ); ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L74) #### Parameters * `message: string` The content of the notification. * `data: object` Additional data. Properties * `data.namespace?: string` Additional event namespace. * `data.title?: string` The title of the notification. Defaults to `{}` #### Returns * `void` ### `showWarning( message, data = { data.namespace?, data.title? } ) → void` Shows a warning notification. By default, it fires the [`show:warning` event](#event-show:warning) with the given `data`. The event namespace can be extended using the `data.namespace` option. For example: ```typescript showWarning( 'Image upload error.', { namespace: 'upload:image' } ); ``` will fire the `show:warning:upload:image` event. You can provide the title of the notification: ```typescript showWarning( 'Image upload error.', { title: 'Upload failed' } ); ``` Note that each unhandled and not stopped `warning` notification will be displayed as a system alert. The plugin responsible for displaying warnings should `stop()` the event to prevent displaying it as an alert: ```typescript notifications.on( 'show:warning', ( evt, data ) => { // Do something with the data. // Stop this event to prevent displaying it as an alert. evt.stop(); } ); ``` You can attach many listeners to the same event and `stop()` this event in a listener with a low priority: ```typescript notifications.on( 'show:warning', ( evt, data ) => { // Show the warning in the UI, but do not stop it. } ); notifications.on( 'show:warning', ( evt, data ) => { // Log the warning to some error tracker. // Stop this event to prevent displaying it as an alert. evt.stop(); }, { priority: 'low' } ); ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L179) #### Parameters * `message: string` The content of the notification. * `data: object` Additional data. Properties * `data.namespace?: string` Additional event namespace. * `data.title?: string` The title of the notification. Defaults to `{}` #### Returns * `void` ### `stopDelegating( event?, emitter? ) → void` _(inherited)_ Stops delegating events. It can be used at different levels: * To stop delegating all events. * To stop delegating a specific event to all emitters. * To stop delegating a specific event to a specific emitter. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L552) #### Parameters * `event?: string` The name of the event to stop delegating. If omitted, stops it all delegations. * `emitter?: Emitter` (requires `event`) The object to stop delegating a particular event to. If omitted, stops delegation of `event` to all emitters. #### Returns * `void` ### `stopListening( emitter?, event?, callback? ) → void` _(inherited)_ Stops listening for events. It can be used at different levels: * To stop listening to a specific callback. * To stop listening to a specific event. * To stop listening to all events fired by a specific object. * To stop listening to all events fired by all objects. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L497) #### Parameters * `emitter?: Emitter` The object to stop listening to. If omitted, stops it for all objects. * `event?: string` (Requires the `emitter`) The name of the event to stop listening to. If omitted, stops it for all events from `emitter`. * `callback?: Function` (Requires the `event`) The function to be removed from the call list for the given `event`. #### Returns * `void` ### `unbind( unbindProperties ) → void` _(inherited)_ Removes the binding created with [`bind`](#function-bind:SINGLE_BIND). ```typescript // Removes the binding for the 'a' property. A.unbind( 'a' ); // Removes bindings for all properties. A.unbind(); ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1090) #### Parameters * `unbindProperties: Array<'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'destroy' | 'context' | 'init' | 'showSuccess' | 'showInfo' | 'showWarning'>` Observable properties to be unbound. All the bindings will be released if no properties are provided. #### Returns * `void` ### `_showNotification( data = { data.message, data.namespace?, data.title?, data.type } ) → void` _(private)_ Fires the `show` event with the specified type, namespace and message. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L200) #### Parameters * `data: object` The message data. Properties * `data.message: string` The content of the notification. * `data.namespace?: string` Additional event namespace. * `data.title?: string` The title of the notification. * `data.type: NotificationEventType` The type of the message. #### Returns * `void` ## Events ### `change:{property}( eventInfo, name, value, oldValue )` _(inherited)_ Fired when a property changed value. ```typescript observable.set( 'prop', 1 ); observable.on>( 'change:prop', ( evt, propertyName, newValue, oldValue ) => { console.log( `${ propertyName } has changed from ${ oldValue } to ${ newValue }` ); } ); observable.prop = 2; // -> 'prop has changed from 1 to 2' ``` [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1190) #### Parameters * `eventInfo: EventInfo` An object containing information about the fired event. * `name: string` The property name. * `value: TValue` The new property value. * `oldValue: TValue` The previous property value. ### `set:{property}( eventInfo, name, value, oldValue )` _(inherited)_ Fired when a property value is going to be set but is not set yet (before the `change` event is fired). You can control the final value of the property by using the [event's `return` property](module_utils_eventinfo-EventInfo.md#member-return). ```typescript observable.set( 'prop', 1 ); observable.on>( 'set:prop', ( evt, propertyName, newValue, oldValue ) => { console.log( `Value is going to be changed from ${ oldValue } to ${ newValue }` ); console.log( `Current property value is ${ observable[ propertyName ] }` ); // Let's override the value. evt.return = 3; } ); observable.on>( 'change:prop', ( evt, propertyName, newValue, oldValue ) => { console.log( `Value has changed from ${ oldValue } to ${ newValue }` ); } ); observable.prop = 2; // -> 'Value is going to be changed from 1 to 2' // -> 'Current property value is 1' // -> 'Value has changed from 1 to 3' ``` **Note:** The event is fired even when the new value is the same as the old value. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1228) #### Parameters * `eventInfo: EventInfo` An object containing information about the fired event. * `name: string` The property name. * `value: TValue` The new property value. * `oldValue: TValue` The previous property value. ### `show( eventInfo, data )` Fired when one of the `showSuccess()`, `showInfo()`, `showWarning()` methods is called. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L226) #### Parameters * `eventInfo: EventInfo` An object containing information about the fired event. * `data: NotificationShowEventData` The notification data. ### `show:info( eventInfo, data )` Fired when the `showInfo()` method is called. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L245) #### Parameters * `eventInfo: EventInfo` An object containing information about the fired event. * `data: NotificationShowEventData` The notification data. ### `show:success( eventInfo, data )` Fired when the `showSuccess()` method is called. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L237) #### Parameters * `eventInfo: EventInfo` An object containing information about the fired event. * `data: NotificationShowEventData` The notification data. ### `show:warning( eventInfo, data )` Fired when the `showWarning()` method is called. When this event is not handled or stopped by `event.stop()`, the `data.message` of this event will be automatically displayed as a system alert. [See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/notification/notification.ts#L256) #### Parameters * `eventInfo: EventInfo` An object containing information about the fired event. * `data: NotificationShowEventData` The notification data. --- Full index of the CKEditor 5 API reference: [llms.txt](llms.txt)